1. Field of the Invention
This invention relates to a multiple contact electrical connector, and in particular to an improved High Speed Serial Data Connector (HSSDC) system made up of a modular plug and a receptacle having a polarization slot and a ferrite block filter.
2. Description of Related Art
The HSSDC system was developed to carry data over Ethernet connections at full duplex rates of up to four Gigabits per second, over extended cable lengths of up to ten kilometers. Although not yet subject to a formal IEEE standard, the IEEE draft proposal calls for eight signal lines and, in the case of extended length cable connections, an equalizer board connected between the contacts of the plug connector and corresponding contacts of the cable.
In general, the HSSDC connector design is similar to other network cable connector designs, but the presence of an equalizer board in the plug connector, and the relative high data rates of the proposed HSSDC standard, present a number of new problems. Although the problems are of particular concern with respect to HSSDC connectors, however, those skilled in the art will appreciate that the solutions to the problems may also have applicability to other types of connectors, and in particular to other high speed multiple contact data cable connectors.
The first problem is the difficulty in assembling the contacts of the plug connector to the equalizer board. Currently, both the connector contacts and cable conductors must be soldered to the equalizer board before placement of the entire assembly in the connector housing. As a result special handling of the cable and board is required, greatly complicating the manufacturing process. While modular designs, including modular designs utilizing solderless contact arrangements, have previously been proposed, the prior designs have either pre-positioned the connector contacts in the module, as is common in the case of RJ contacts, or provided a separate circuit board module for various filter components, as in the case of SCSI or RJ connectors. Neither of these two solutions is suitable for use in an HSSDC connector system because of the configuration of the contacts which, unlike RJ contacts, extend generally horizontally from the equalizer board, leaving them vulnerable to damage during assembly, and because of the design of the connector housing which, as a result of the high data rates, must completely enclose the equalizer board, thereby making post assembly termination of the cable to the circuit board impractical.
The second problem is that current assembly techniques require, in the case of connectors that do not include an equalizer board, termination of the connector contacts directly to the cable contacts before insertion into the connector, which requires a separate assembly line. Even if a conventional modular design could be used for such connectors, the problem would remain that separate assembly procedures or different modules are required for equalized and non-equalized connectors.
The third problem is the problem of polarization of the HSSDC system. Because of the wide variety of devices that could use HSSDC type connections, it is possible that devices could be cross-connected. It would thus be desirable to include a way to prevent otherwise identical HSSDC plugs from being plugged into the same receptacle.
Finally, the fourth problem involves the general problem of shielding and filtering the contacts. While the HSSDC cable, plug, and receptacle are all shielded against radio frequency (RF) interference, the currently proposed connector design makes no allowance for filtering out spurious signals that might result from electro-magnetic interference (EMI), which can be significant due to the lengths of cable involved. Because of the unique configuration of the HSSDC system connectors, the advantages of placing an EMI filter within the HSSDC format connector have not previously been recognized, even though EMI filter arrangements are well known in the context of RJ, SCSI, and other less well-shielded cable/connector systems. In addition, conventional filtering arrangements often add significantly to the cost of assembly because of the small size of the filters and the need to terminate them to individual contacts.